Apparatus and method for managing thermally induced motion of a probe card assembly

ABSTRACT

A probe card assembly can include a probe head assembly having probes for contacting an electronic device to be tested. The probe head assembly can be electrically connected to a wiring substrate and mechanically attached to a stiffener plate. The wiring substrate can provide electrical connections to a testing apparatus, and the stiffener plate can provide structure for attaching the probe card assembly to the testing apparatus. The stiffener plate can have a greater mechanical strength than the wiring substrate and can be less susceptible to thermally induced movement than the wiring substrate. The wiring substrate may be attached to the stiffener plate at a central location of the wiring substrate. Space may be provided at other locations where the wiring substrate is attached to the stiffener plate so that the wiring substrate can expand and contract with respect to the stiffener plate.

BACKGROUND

FIG. 1A illustrates an exemplary prior art probing system used to testdies (not shown) on a newly manufactured semiconductor wafer 112 orother electronic devices. The probing system of FIG. 1A includes a testhead 104 and a prober 102 (which is shown with a cut-away 126 to providea partial view of the inside of the prober 102). To test the dies (notshown) of the semiconductor wafer 112, the wafer 112 is placed on amoveable stage 106 as shown in FIG. 1A, and the stage 106 is moved suchthat terminals (not shown) on dies (not shown) of the wafer 112 arebrought into contact with probes 124 of a probe card assembly 108.Temporary electrical connections are thus established between the probes124 and dies (not shown) of the wafer 112 to be tested.

Typically, a cable 110 or other communication means connects a tester(not shown) with the test head 104. Electrical connectors 114electrically connect the test head 104 with the probe card assembly 108.The probe card assembly 108 shown in FIG. 1A includes a wiring board120, which can provide electrical connections from connectors 114 to theprobe substrate 122, and the probe substrate can provide electricalconnections to the probes 124.

The cable 110, test head 104, and electrical connectors 114 thus provideelectrical paths between the tester (not shown) and the probe cardassembly 108, and the probe card assembly 108 extends those electricalpaths to the probes 124. Thus, while the probes 124 are in contact withthe terminals (not shown) of the dies (not shown) on the wafer 112,cable 110, test head 104, electrical connectors 114, and probe cardassembly 108 provide a plurality of electrical paths between the tester(not shown) and the dies (not shown). The tester (not shown) writes testdata through these electrical paths to the dies (not shown), andresponse data generated by the dies (not shown) in response to the testdata is returned to the tester (not shown) through these electricalpaths.

It is often advantageous to test the dies (not shown) of the wafer 112at specific temperatures or over a range of temperatures. To this end,heating elements or cooling elements (not shown) may be included in thestage 106 or at other locations in the prober 102 to heat or cool thewafer 112 during testing. Even if heating elements or cooling elements(not shown) are not used, operation of the dies (not shown) of the wafer112 may generate heat. Such heating or cooling from eitherheating/cooling elements (not shown) or from operation of the dies (notshown) may cause the wafer 112 and the probe substrate 122 to expand orcontract, changing the positions of the probes 124 and the terminals(not shown) on the wafer 112, which may cause misalignment between theprobes 124 and terminals (not shown) in a plane that is generallyhorizontal in FIG. 1A. (This horizontal plane is in the directionslabeled “x, y” in FIG. 1A and will hereinafter be referred to as “x, y”movement. In FIG. 1A, the direction labeled “x” is horizontal across thepage, the direction labeled “y” is horizontal into and out of the page,and the direction labeled “z” is vertical. These directions are relativeand for convenience and are not to be taken as limiting.) If such “x, y”misalignment becomes too great, the probes 124 will no longer be able tocontact all of the terminals (not shown).

The use of heating elements or cooling elements (not shown) to heat orcool the wafer 112 during testing, and/or the generation of heat by thedies of the wafer 112 as they are tested, may also cause a thermalgradient between the side of the probe card assembly 108 that faces thewafer 112 (hereinafter a side of the probe card assembly that faces thewafer 112 will be referred to as the “front-side” or the “wafer-side”)and the opposite side of the probe card assembly (hereinafter theopposite side of the probe card assembly will be referred to as the“back-side” or the “tester side”). Such thermal gradients can cause theprobe card assembly 108 to bow or warp. If such bowing is towards thewafer 112, the probe card assembly 108 may press against the wafer 112with too much force and damage the wafer 112 or probe card assembly 108.If such bowing is away from the wafer 112, some or all of the probes 124may move (in a generally vertical direction with respect to FIG. 1A) outof contact with the terminals (not shown) on the wafer 112. If theprobes 124 do not contact the terminals (not shown), the dies (notshown) on the wafer 112 will falsely test as failed. (Movement to oraway from the wafer 112 is labeled the “z” direction in FIG. 1A and willhereinafter be referred to as “z” movement.)

Often, immediately following installation of a probe card assembly 108in a prober 102 with a heated (or cooled) stage 106, the probe cardassembly 108 will undergo thermally induced movement. The movement stopsand the position of the probe card assembly 108 stabilizes only after asufficient temperature equilibrium is reached between the front-side andback-side of the probe card assembly 108. Of course, such an equilibriumneed not be a perfect equilibrium in which the front-side temperature ofthe probe card assembly 108 exactly equals the back-side temperature;rather, the front-side temperature and the back-side temperature needonly be sufficiently close that the structure of the probe card assembly108 is able to resist thermal movement. The time required to reach sucha temperature equilibrium or near equilibrium is often referred to as“thermal equilibrium time” or “thermal soak time.”

Typically, the probe substrate 122 is attached directly to the wiringboard 120, which in turn is attached to a test head plate 121 on theprober 102. A shown in FIG. 1B, the test head plate 121 forms an opening132 in the prober 102 into which the probe substrate 122 fits (asgenerally shown in FIG. 1A). The test head plate 121 may include holes134 for bolts that secure the probe card assembly 108 to the test headplate 121. (Clamping or techniques other than bolting may be used toattached the probe card assembly 108 to the test head plate 121.) Thewiring board 120 is typically made of a printed circuit board material,which is particularly susceptible to thermally induced “x, y” and “z”movements. Improved techniques for counteracting thermally inducedmovements (including “x, y” movement and “z” movement) of a probe cardassembly and reducing thermal equilibrium time would be desirable.

SUMMARY

According to some embodiments of a probe card assembly, a probe headassembly can be attached directly to a metallic stiffener plate, whichcan be configured to attach the probe card assembly to a prober. Awiring substrate can provide electrical connections to the probe headassembly. The wiring substrate can be attached to the stiffener platesuch that the wiring substrate can expand and contract with respect tothe stiffener plate. The stiffener plate can have a greater mechanicalstrength and/or stiffness than the wiring substrate and can thus be lesssusceptible to thermally induced movement and/or deformation than thewiring substrate. The stiffener plate can also have a lower coefficientof thermal expansion than the wiring substrate.

According to some embodiments of a probe card assembly, a trussstructure can be attached to the stiffener plate to further strengthenand/or stiffen the stiffener plate against thermally induced movement.Adjustment mechanisms may be included for adjusting an orientationand/or shape of the stiffener plate with respect to the truss structure.

According to some embodiments of a probe card assembly, a stud structurecan be attached to the truss structure. While the probe card assembly isattached to a prober, a gripper on a test head can grip the studstructure, adding the strength of the test head to the truss structureto yet further strengthen the probe card assembly against thermallyinduced movement.

According to some embodiments of a probe card assembly, a heat sink canbe provided for facilitating transfer of heat from the front-side of theprobe card assembly to the back-side of the probe card assembly. Fans orheat pumps may be used in addition to or in place of the heat sink.

According to some embodiments of a probe card assembly, temperaturecontrol devices can be provided in a probe head assembly to heat and/orcool the probe head assembly during testing of an electronic device. Byso doing, the probe head assembly can be expanded or contracted to matchthermally induced expansion or contraction of the electronic device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a side view of an exemplary prior art prober, test head,and probe card assembly. A cut-out provides a partial view of the insideof the prober.

FIG. 1B shows a perspective view of the prober and test head of FIG. 1Awithout a probe card assembly.

FIG. 2A shows a top view of an exemplary probe card assembly accordingto some embodiments of the invention.

FIG. 2B shows a bottom view of the probe card assembly of FIG. 2A.

FIG. 2C shows a side cross-sectional view of the probe card assembly ofFIG. 2A.

FIG. 3A shows the wiring board of the probe card assembly of FIG. 2Aaccording to some embodiments of the invention.

FIG. 3B shows the stiffener plate of the probe card assembly of FIG. 2Aaccording to some embodiments of the invention.

FIG. 4 is a schematic view of the wiring substrate and probe headassembly of FIG. 2A according to some embodiments of the invention.

FIG. 5A illustrates an exemplary probe head assembly and exemplaryattachment/adjustment mechanisms according to some embodiments of theinvention.

FIG. 5B illustrates an exemplary arrangement of attachment/adjustmentmechanisms on a space transformer of the probe head assembly of FIG. 5Aaccording to some embodiments of the invention.

FIG. 6 is a simplified block diagram illustrating another exemplaryprobe card assembly according to some embodiments of the invention.

FIG. 7A shows a top view of the truss structure and stiffener plate ofthe probe card assembly of FIG. 6 according to some embodiments of theinvention.

FIG. 7B shows a side cross-sectional view of the truss structure andstiffener plate of the probe card assembly of FIG. 6 according to someembodiments of the invention.

FIG. 8 illustrates a block diagram of a system for automaticallyadjusting an orientation of the stiffener plate with respect to thetruss structure of FIG. 7A according to some embodiments of theinvention.

FIG. 9A illustrates yet another exemplary probe card assembly accordingto some embodiments of the invention. The probe card assembly is showninstalled in an exemplary prober according to some embodiments of theinvention.

FIG. 9B shows a detailed view of the stud structure and gripper of FIG.9A.

FIG. 10A shows a top view of still another exemplary probe card assemblyaccording to some embodiments of the invention.

FIG. 10B illustrates a bottom view of the probe card assembly of FIG.10A.

FIG. 10C illustrates a side cross-sectional view of the probe cardassembly of FIG. 10A.

FIG. 11A shows a top view of a further exemplary probe card assemblyaccording to some embodiments of the invention.

FIG. 11B illustrates a bottom view of the probe card assembly of FIG.11A.

FIG. 11C illustrates a side cross-sectional view of the probe cardassembly of FIG. 11A.

FIG. 12A shows a top view of yet a further exemplary probe card assemblyaccording to some embodiments of the invention.

FIG. 12B illustrates a side cross-sectional view of the probe cardassembly of FIG. 12A.

FIGS. 13A, 13B, and 13C show side partial views of still anotherexemplary probe card assembly and a stage with a wafer to be testedaccording to some embodiments of the invention.

FIG. 14 illustrates an exemplary probe head assembly that may be usedwith the probe card assembly of FIGS. 13A, 13B, and 13C according tosome embodiments of the invention.

FIG. 15 illustrates an exemplary process that may be used to monitor andcorrect alignment of probes and die terminals during testing of the diesover a range of temperatures according to some embodiments of theinvention.

FIG. 16 illustrates an exemplary system on which the process of FIG. 15may be implemented according to some embodiments of the invention.

FIG. 17 illustrates an exemplary prober, probe card assembly, and waferthat illustrates an example of the monitor of FIG. 16 according to someembodiments of the invention.

FIG. 18 illustrates an exemplary probe head assembly according to someembodiments of the invention.

FIG. 19 illustrates an exemplary probe card assembly showing acombination of features from other probe card assemblies describedherein according to some embodiments of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

This specification describes exemplary embodiments and applications ofthe invention. The invention, however, is not limited to these exemplaryembodiments and applications or to the manner in which the exemplaryembodiments and applications operate or are described herein.

FIGS. 2A, 2B, 2C, 3A, and 3B illustrate an exemplary probe card assembly200 configured to resist “z” direction thermal movement according tosome embodiments of the invention. (As used herein, movement includesmovement, deformation, bending, warping, etc.) FIG. 2A is a top view,FIG. 2B is a bottom view, and FIG. 2C is a side cross-sectional view ofthe probe card assembly 200. (In FIGS. 2A and 2B, the “x” direction ishorizontal across the page, the “y” direction is vertical on the page,and the “z” direction, although shown slightly askew, is perpendicularto—that is, into and out of—the page; in FIG. 2C, the “x” direction ishorizontal across the page, the “y” direction, although shown slightlyaskew, is perpendicular—that is, into and out of—the page, and the “z”direction is vertical on the page. These directions are provided forpurposes of illustration and discussion only, however, and are notlimiting.) FIG. 3A illustrates a top view of just the wiring substrate204, and FIG. 3B illustrates a top view of just the stiffener plate 202.Although not limited to use with the prober 102 and test head 104 ofFIGS. 1A and 1B, the exemplary probe card assembly 200 shown in FIGS.2A, 2B, and 2C may be used in the prober 102 and test head 104 of FIGS.1A and 1B in place of probe card assembly 108.

As shown in FIGS. 2A, 2B, and 2C, the probe card assembly 200 caninclude a stiffener plate 202, a wiring substrate 204, and a probe headassembly 222. As shown in FIGS. 2B and 2C, the probe head assembly 222can include a plurality of probes 224, which like probes 124 shown inFIG. 1A, can be configured to contact terminals (not shown) onsemiconductor dies (not shown) to be tested. Probes 224 (or any of theprobes discussed herein) can be resilient, conductive structures. Probes224 may be a resilient, conductive structure. Non-limiting examples ofsuitable probes 224 include composite structures formed of a core wirebonded to a conductive terminal (not shown) on a probe head assembly(e.g., like probe head assembly 222) that is over coated with aresilient material as described in U.S. Pat. No. 5,476,211, U.S. Pat.No. 5,917,707, and U.S. Pat. No. 6,336,269. Probes 224 may alternativelybe lithographically formed structures, such as the spring elementsdisclosed in U.S. Pat. No. 5,994,152, U.S. Pat. No. 6,033,935, U.S. Pat.No. 6,255,126, U.S. Pat. No. 6,945,827, U.S. Patent ApplicationPublication No. 2001/0044225, and U.S. Patent Application PublicationNo. 2004/0016119. Still other non-limiting examples of probes 224 aredisclosed in U.S. Pat. No. 6,827,584, U.S. Pat. No. 6,640,432, U.S. Pat.No. 6,441,315, and U.S. Patent Application Publication No. 2001/0012739.Other non-limiting examples of probes 224 include conductive pogo pins,bumps, studs, stamped springs, needles, buckling beams, etc.

The dies (not shown) to be tested can be dies of an unsingulatedsemiconductor wafer (e.g., like wafer 112 of FIG. 1A), singulated dies(e.g., held in a carrier (not shown)), dies forming a multi-chip module,or any other arrangement of dies to be tested. As will be seen, thewiring substrate 204 can provide electrical connections to the probehead assembly 222, and the stiffener plate 202 can provide mechanicalstability to the probe head assembly 222.

As shown in FIGS. 2A, 2B, and 2C, the wiring substrate 204 can includetest head connectors 208, which can be for receiving electricalconnectors 114 and thereby making electrical connections with the testhead 104 (see FIG. 1A). Test head connectors 208 may be, for example,zero-insertion-force connectors or pogo pads for engaging pogo pins fromthe test head 104. As shown in FIG. 4 (which shows a schematic depictionof wiring substrate 204 and probe head assembly 222), electrical paths402 can be provided through the wiring substrate 204 to electricalconnections 404, which in turn can be connected to electrical paths 406through the probe head assembly 222 to the probes 224. The wiringsubstrate 204 and probe head assembly 222, along with electricalconnections 404, thus provide a plurality of electrical paths betweentest head connectors 208 and probes 224.

Referring again to FIGS. 2A, 2B, and 2C, the wiring substrate 204 can beselected for its ability to provide electrical paths (402 in FIG. 4) asdescribed above. For example, the wiring substrate 204 may be a printedcircuit board material, which as known in the art, may comprise multiplelayers (not shown) of an insulating material on which conductive traces(not shown) can be formed with vias (not shown) interconnecting traces(not shown) on different layers.

The probe head assembly 222 can be selected for its ability to functionas a platform for the probes 224 and to provide electrical paths (406 inFIG. 4) to the probes 224. Probe head assembly 222 may be as simple as asingle substrate with traces (not shown) and vias (not shown) formingelectrical paths 406 (see FIG. 4). Alternatively, probe head assembly222 may be more complex. For example, probe head assembly 222 maycomprise a plurality of substrates.

FIG. 5A illustrates an example of a complex probe head assembly 222 thatmay be used with the probe card assembly 200 shown in FIGS. 2A, 2B, and2C. In FIG. 5A, the probe head assembly 222 can include two spacetransformers 518 and two interposers 520. Each space transformer 518 canbe mechanically attached to the stiffener plate 202 (shown in partialview only in FIG. 5A) by differential screw assemblies 502 (which willbe described in more detail below). Each space transformer can includeprobes 224 for contacting an electronic device (not shown) to be tested.Interposers 520 can provide electrical connections between the wiringsubstrate 204 and the space transformers 518. Each interposer 520 cancomprise a wiring board (e.g., made of printed circuit board material)and electrically conductive spring elements 512 and 508 extending fromeither side of the interposer 520 and electrical paths 510 (e.g.,conductive vias) through the interposer 520 provide the electricalconnections between the wiring substrate 204 and the space transformers518. Conductive spring elements 512 and 508 may be any resilient,conductive structures. For example, conductive spring elements 512 and508 can be like probes 224.

Space transformers 518 may be made of layers (not shown) of ceramic ororganic material, and electrical paths 522 through the spacetransformers 518 may comprise conductive traces (not shown) on thelayers (not shown) with vias (not shown) connecting traces on differentlayers. Nonlimiting examples of probe head assemblies that include atleast one interposer and at least one space transformer are disclosed inU.S. Pat. No. 5,974,662, U.S. Pat. No. 6,483,328, and U.S. Pat. No.6,509,751. The following disclose other examples of probe headassemblies that can be used as probe head assembly 222: U.S. Pat. No.5,806,181, U.S. Pat. No. 6,690,185, U.S. Pat. No. 6,640,415, U.S. PatentApplication Publication No. 2001/0054905, U.S. Patent ApplicationPublication No. 2002/0004320, and U.S. Patent Application PublicationNo. 2002/0132501. As another example, probe head assembly can comprise aplurality of probe heads each having a probe array and positioned toform a large array of probes. In such a probe head assembly, each probehead can be independently positionable and adjustable. Non-limitingexamples of such probe head assemblies are disclosed in U.S. patentapplication Ser. No. 11/165,833, entitled “Method And Apparatus ForAdjusting A Multi-Substrate Probe Structure,” filed Jun. 24, 2005.

Returning to a discussion of the probe card assembly 200 of FIGS. 2A,2B, and 2C and referring now to the mechanical function that can beprovided by the stiffener plate 202, as shown in FIGS. 2A, 2B, and 2C,mechanical fasteners 216 can mechanically attach the probe head assembly222 to the stiffener plate 202. As shown in FIG. 2C, mechanicalfasteners 216 pass through holes 242 in the wiring substrate 204.Consequently, the probe head assembly 222 is not attached directly tothe wiring substrate 204. In this way, the wiring substrate 204 can alsobe thermally decoupled from the probe head assembly 222.

Mechanical fasteners 216 may comprise any suitable means for securingthe probe head assembly 222 to the stiffener plate. For example, themechanical fasteners 216 may be as simple as screws or bolts 216 (asshown in FIG. 2C) that pass through threaded holes (314 in FIG. 3B) inthe stiffener plate and engage threaded holes (not shown) in the probehead assembly 222. Alternatively, the mechanical fasteners 216 may bemore complicated structures that provide additional functions. FIG. 5Aillustrates an example of mechanical fasteners that can be configurednot only to secure the probe head assembly 222 to the stiffener plate202 but also to control the orientation of the probe head assembly 222(and thus the probes 224) with respect to the stiffener plate 202.

In FIG. 5A, the mechanical fasteners that secure probe head assembly 222(interposers 510 and space transformers 518 in FIG. 5A) to the stiffenerplate 202 can be differential screw assemblies 502. Each differentialscrew assembly 502 can include a screw (or bolt) 504 that threads into anut 506 that is itself threaded into the stiffener plate 202. Thus, theinside of nut 506 is threaded to receive screw 504, and the outside ofnut 506 is also threaded so that nut 506 can thread into stiffener plate202. As shown in FIG. 5A, the screw 504 passes through a hole 242 in thewiring substrate 204 and a hole 514 in the interposer 520. The screw 504threads into a threaded stud 516 attached to a space transformer 518.Hole 242 through the wiring substrate 204 can include extra space, whichas will be discussed below, allows the wiring substrate 204 to move(e.g., expand and contract) with respect to the stiffener plate 202 andthe probe head assembly 222.

By adjusting one of the nuts 506 of one of the assemblies 502, theportion of the space transformer 518 to which the corresponding threadedstud 516 is attached can be pulled toward the stiffener plate 202 orpushed away from the stiffener plate 202. By utilizing a plurality ofsuch differential screw assemblies 502 each attached to a differentportion of the space transformer 518, the planar orientation of thespace transformer 518 with respect to the stiffener plate 202 may beadjusted.

FIG. 5B illustrates on exemplary space transformer 518 to which ninethreaded studs 516 can be attached. FIG. 5B also shows nine screws 504threaded into nine nuts 506 and the nine studs 516. (For clarity andease of illustration, other elements, such as stiffener plate 202, arenot shown in FIG. 5B. Nevertheless, as described above and shown in FIG.5A, nuts 506 thread into stiffener plate 202.) Rotating a nut 506 in afirst direction pulls the region of the space transformer 518 to whichthe corresponding threaded stud 516 is attached towards the stiffenerplate 202. Conversely, rotating the nut 506 in the opposite directionpushes the region of the space transformer 518 to which the threadedstud 516 is attached away from the stiffener plate 202. As should beapparent, the planar orientation and even the shape of the surface 540of the space transformer 518 to which the probes 224 are attached can bealtered with respect to the stiffener plate 202. The pitch of the screws502, and the corresponding pitch of the inner threads of the nut 506,and the pitch of the outer threads of the nut 506 can be selected toallow for fine adjustment of the positions of studs 516 with respect tostiffener plate 202.

Because, as shown in FIG. 2C, the stiffener plate 202 of the probe cardassembly is attached to the head plate 121 of the prober 102 and theprobes 224 (which may be disposed in a two-dimensional array) areattached to a space transformer 518 (which forms part of the probe headassembly 222 shown in FIG. 2C), adjusting the planar orientation orshape of the space transformer 518 with respect to the stiffener plate202 adjusts the planar orientation of the tips of the probes 222 withrespect to the head plate 121 so that, while the probe card assembly 200is attached to the head plate 121, the tips can be planarized withrespect to the terminals (not shown) of the dies being tested.

The number and placement of differential screw assemblies 502 shown inFIGS. 5A and 5B are exemplary only. More or fewer of such assemblies 502may be used, and those assemblies 502 may be disposed in patterns otherthan the orientation shown in FIG. 5A and the orientation shown in FIG.5B. The number and spacing of the studs 516 can be selected in anynumber of ways. For example, the number and spacing of the studs 516 canbe selected using a solid model of the system and finite elementanalysis to perform a sensitivity study. Moreover, differential screwassemblies 502 need not be used. Indeed, other mechanisms for securingthe probe head assembly 222 to the stiffener plate 202 may be used. Forexample, split nut differential screw assemblies may be used in place ofthe screw assemblies 502. The split nut can allow the threads to bepreloaded, which may prevent backlash. As another example, some of thescrew assemblies 502 may be replaced with assemblies that push the spacetransformer 518 away from the stiffener plate 202 but are not able topull the space transformer 518 towards the stiffener plate 202.

Returning again to the discussion of the probe card assembly 200 ofFIGS. 2A, 2B, and 2C, as shown in FIG. 2C, in the probe assembly 200,the stiffener plate 202—rather than the wiring substrate 204—can beconfigured to be secured to the test head plate 121 of the prober 102(see FIG. 1B). In the exemplary probe card assembly 200 shown in FIGS.2A, 2B, 2C, the stiffener structure 202 can include radial arms 210. Asbest seen in FIGS. 2B and 2C, the stiffener plate 202 also can includetabs 226 disposed in slots 302 in the wiring substrate 204. Holes 206and 228 through the radial arms 210 and the tabs 226 correspond to theholes 134 in the test head plate 121 (see FIG. 1B), and the probe cardassembly 200 can be attached to the test head plate 121 (see FIG. 1B) bybolts 142 that pass through the holes 206 and 228 in the radial arms 210and tabs 226 and through holes 134 in the tester head plate 121. (InFIG. 2C, the prober head plate 121 is shown in dashed lines as arebolt/nut pairs for bolting the probe card assembly 200 to the proberhead plate 121.)

It should thus be apparent that, because the stiffener plate 202 isbolted to the test head plate 121 and the probe head assembly 222 isattached to the stiffener plate 202, the stiffener plate 202 can providemechanical stability to the probe head assembly 222. The stiffener plate202 may be selected for its strength and ability to resist thermalmovement. For example, the stiffener plate 202 (and tabs 226) maycomprise metal (e.g., aluminum), which is typically stronger and moreresistant to movement, bowing, warping, etc. than a wiring substrate 204would be (e.g., as discussed above, the wiring substrate 204 istypically made of printed circuit board materials). Other non-limitingexamples of materials from which the stiffener plate 202 (and tabs 226)can be made include steel, titanium, nickel, ex invar, kovar, graphiteepoxy, metal matrix materials, ceramics, etc. In addition, alloys of anyof the foregoing materials or mixtures of any of the foregoing materialswith other materials can be used. It should be apparent that thestiffener plate 202 and tabs 226 can form a metallic structure thatattaches the probe head assembly 222 to the prober head plate 121.

FIGS. 2A, 2B, 2C, 3A, and 3B also illustrate another technique that maybe implemented to reduce thermally induced movement of the probes 224.As mentioned above, typical wiring substrates 204 can be susceptible tothermally induced movement. In the example illustrated in FIGS. 2A, 2B,2C, 3A, and 3B, the wiring substrate 204 can be attached to thestiffener plate 202 such that the wiring substrate 204 can expand andcontract radially. That is, the wiring substrate 204 can move radiallywith respect to the stiffener plate 202 and the probe head assembly 222.This reduces the forces on the stiffener plate 202 caused by expansionor contraction of the wiring substrate 204 in response to changes in theambient temperature.

As shown in FIGS. 2A and 2C, the wiring substrate 204 can be secured tothe stiffener plate 202 at one location (e.g., generally at the center)of the wiring substrate 204. As shown in FIGS. 2A, 2C, 3A, and 3B, ascrew or bolt 214 may be used to secure the wiring substrate 204 to thestiffener plate 202. Such a screw or bolt 214 may pass through (orthread through) hole 316 (see FIG. 3B) in the stiffener plate 202 andthread into a threaded hole (or insert) 252 in the wiring substrate 204(see FIG. 3A).

Spaces and other provisions can be provided for allowing the wiringsubstrate 204 to expand radially away from the screw 214 or contractradially toward the screw 214. For example, in FIGS. 2A, 2B, and 2C,additional bolts 212 and nuts 232 prevent the wiring substrate 204 fromrotating with respect to the stiffener plate 202. As best seen in FIG.3A, the holes 246 in the wiring substrate 204 through which the bolts212 pass can be elongate to provide space for expansion and contractionof the wiring substrate 204. Extra space can similarly be provided inthe holes 242 in the wiring substrate 204 through which the mechanicalfasteners 216 pass that secure the probe head assembly 222 to thestiffener plate 202. The extra space allows the wiring substrate 204 toexpand and contract. Extra space may similarly be provided in the slots302 in the wiring substrate 204 to allow for expansion and contractionof the wiring substrate 204. Lubrication, bearings, or other means (notshown) may optionally be provided on surfaces of the wiring substrate204 to facilitate movement of the wiring substrate 204 with respect tothe stiffener plate 202 and the probe head assembly 222.

FIG. 6 illustrates a simplified block diagram of another exemplary probecard assembly 600 configured to resist thermal movement according tosome embodiments of the invention. The probe card assembly 600 can begenerally similar to probe card assembly 200 but with the addition oftruss structure 604. The stiffener plate 202, wiring substrate 204, andprobe head assembly 222 of probe card assembly 600 can be the same aslike named and numbered elements in probe card assembly 200 and, forsimplicity and ease of illustration, are shown in FIG. 6 in blockdiagram format without the details shown and discussed above withrespect to probe card assembly 200. As shown in FIG. 6 (which shows aside view of probe card assembly 600), a truss structure 604 can besecured to the stiffener plate 202. As will be seen, truss structure 604can be an additional stiffening structure that helps probe card assembly600 further resist thermally induced “z” movement and/or mechanicalmovement.

FIG. 7A and FIG. 7B, which show only the truss structure 604 and thestiffener plate 202, illustrate details of an exemplary truss structure604. (FIG. 7A shows a top view and FIG. 7B shows a cross-sectional sideview of the truss structure 604 and the stiffener plate 202.)

As shown in FIGS. 7A and 7B, truss structure 604 can be secured to thestiffener plate 202. The truss structure 604 may be secured to thestiffener plate 202 using any suitable means. In FIGS. 7A and 7B, aplurality of screws (or bolts) 614 pass through holes (not shown) in thetruss structure 604 and thread into corresponding holes (not shown) inthe stiffener plate 202. In the exemplary truss structure 604 shown inFIGS. 7A and 7B, some of screws 614 pass through the body of the trussstructure 604 and some of screws 614 pass through arms 628 that extendfrom the body of the truss structure 604.

Truss structure 604 can be designed to create, in combination withstiffener plate 202, a composite structure having a stiffness-per-weightratio that can be greater than could be achieved if truss structure 604and stiffener plate 202 were a single, solid structure. Truss structure604 can include empty spaces rather than being solid. The exemplarytruss structure 604 shown in FIGS. 7A and 7B can include a plurality ofgenerally square shaped empty spaces 620 and a plurality of generallyrectangular or flatted-oval shaped empty spaces 618. Of course, however,the number and shape of the empty spaces is not critical and any numberand shape of empty spaces may be used. The empty spaces 618, 620 mayprovide access to mechanical fasteners 216 (not shown in FIGS. 6, 7A, or7B). For example, in FIG. 7A, holes 314 in stiffener plate 202 formechanical fasteners 216 can be visible through some of thesquare-shaped empty spaces 620.

Because the structure 604 can include empty spaces 618 and 620, it isnot as heavy as a solid structure would be. The mechanical strength—thatis, the stiffness contribution—can be, however, generally a function ofthe thickness of the structure 604. Thus, the fact that the structure604 has empty spaces 618 and 620 means that, for a given thickness, thetruss structure 604 weighs less than a solid structure but can providegenerally the same amount of mechanical strength as a solid structure.

Because the truss structure 604 adds stiffening strength to the probecard assembly 200, the stiffener plate 202 may be made thinner.Generally speaking, the thinner the stiffener plate 202, the shorter thethermal equilibrium time of the probe assembly 600. As discussed above,immediately following installation of a probe card assembly in a prober(e.g., 102 of FIG. 1A) with a heated (or cooled) stage 106, the probecard assembly typically undergoes thermally induced movement. Theposition of the probe card assembly stabilizes (that is, significantmovement of the probe card assembly stops) only after a sufficienttemperature equilibrium is reached between the front and back-sides ofthe probe card assembly. (In FIG. 6, the front-side is labeled 690 andthe back-side is labeled 692.) As also noted above, such an equilibriumneed not be a perfect equilibrium in which the front-side temperature ofthe probe card assembly equals the back-side temperature; rather, thefront-side temperature and the back-side temperature need only besufficiently close that appreciable movement of the probe card assemblystops. As noted above, the time required to reach such a temperatureequilibrium or near equilibrium is often referred to as thermal soaktime or thermal equilibrium time. The thinner the stiffener plate 202,the less the thermal mass of the stiffener plate 202, and hence theshorter the time to heat (or cool) the stiffener plate 202 to equal orapproximately equal the temperature at the front-side of the probe cardassembly 600. Hence, the thinner the stiffener plate 202, the shorterthe thermal equilibrium time.

The thermal equilibrium time of the probe card assembly 600 may befurther reduced by placing thermally resistive material (not shown)between the stiffener plate 202 and the truss structure 604. Thethermally resistive material (not shown) can thermally isolate the trussstructure 604 from the stiffener plate 202 to eliminate or reduce anycontribution by the truss structure 604 to thermal equilibrium time.Because the truss structure 604 is thermally isolated from the stiffenerplate 202, only the stiffener plate 202—but not also the truss structure604—need reach approximate temperature equilibrium (as discussed above)with the front-side (die-side) of the probe card assembly.

Moreover, because the truss structure 604 has empty spaces 618 and 620,the truss structure 604 can act like a radiator and therefore can remaingenerally at or close to ambient temperature. This is because the spaces618 and 620 in the truss structure 604 can allow air to circulate aboutthe truss structure 604 and carry off any excess heat that builds up inthe truss structure 604 (or warm the truss structure 604 if the air iswarmer than the truss structure 604). This means that the trussstructure 604 itself is unlikely to undergo appreciable levels ofthermally induced movements (in either the “z” or the “z, y”directions), which further removes the truss structure 604 fromcontributing to (and thus increasing) the thermal equilibrium time ofthe probe card assembly 600.

Referring again to FIG. 6, during test, the electronic device 680 beingtested can, of course, be positioned to the front-side 690 of the probecard assembly 600. If the electronic device 680 is heated, the heatsource (not shown) can be also at the front-side 690 of the probe cardassembly 600. A thermal gradient can thus be created from the front-side690 to the back-side 692 of the probe card assembly 600. Such a thermalgradient is represented in FIG. 6 by arrow 682, where the direction ofthe arrow indicates decreasing temperature. If values for the thermalgradient 682 are known or can be approximated, the materials for theprobe head assembly 222, stiffener plate 202, and truss structure 604can be selected so that each expands or contracts by the same amount.That is, the probe head assembly 222 can be made of a material with alow coefficient of thermal expansion such that it expands approximatelya specified distance “d” in response to its expected temperature in thetemperature gradient 682. The stiffener plate 202, which will be at alower temperature than the probe head assembly 222, can be made of amaterial with a higher coefficient of thermal expansion so that it alsoexpands the same specified distance “d” in response to its (lower)expected temperature in the temperature gradient 682. The trussstructure 604, which will be at an even lower temperature than thestiffener plate 202, can be made of a material with an even highercoefficient of thermal expansion so that it also expands the samespecified distance “d” in response to its (even lower) expectedtemperature in the temperature gradient 682.

As shown in FIGS. 7A and 7B, the probe card assembly 600 may includeadjustment mechanisms 616 for adjusting the position of the stiffenerplate 202 with respect to the truss structure 604. The adjustmentmechanisms 616 illustrated in FIGS. 7A and 7B can be differential screwassemblies, each including a screw 632 that threads into a threaded nut634 that is itself threaded into truss structure 604 as generallydescribed above with respect to differential screw assemblies 502. Thatis, the screw 632 also threads into a threaded stud 636 attached to thestiffener plate 202. As also described above with respect todifferential screw assemblies 502, rotation of the nut 634 in onedirection pulls the threaded stud 636 (and thus the portion of thestiffener plate 202 to which the stud 636 is attached) toward the trussstructure 604, and rotation of the nut 634 in the opposite directionpushes the threaded stud 636 (and thus the portion of the stiffenerplate 202 to which the stud 636 is attached) away from the trussstructure 604. As should be apparent, the use of a plurality of suchadjustment mechanisms 616 (e.g., differential screws) disposed atvarious locations on the truss structure 604 and stiffener plate 202,allows the planar orientation and even the shape of the stiffener plate202 to be adjusted with respect to the truss structure 604.

The use of differential screw assemblies as adjustment mechanisms 616are exemplary only; other mechanisms for adjusting the planarorientation of the stiffener plate 202 with respect to the trussstructure 604 may be used. For example, one or more of the differentialscrew assemblies (e.g., 616) may be replaced with a mechanism for onlypushing the stiffener plate 202 away from the truss structure 604. Forexample, the threaded stud 636 may be removed, such that the screw 632presses against the stiffener plate 202 or against a mechanical element(e.g., a metal ball) disposed between the screw 632 and the stiffenerplate 202. In such a configuration, turning the screw 632 in a firstdirection causes the screw 632 to press against the stiffener plate 202and thus push the stiffener plate 202 away from the truss structure 604.Turning the screw 632 the opposite direction, however, simply withdrawsthe screw 632 from the stiffener plate 202 without pulling on thestiffener plate 202. A spring-loaded mechanism (not shown) can beprovided to bias stiffener plate 202 toward truss 604. Regardless of thetype of adjustment mechanism 616 used, more or fewer adjustmentmechanisms 616 than shown in FIGS. 7A and 7B may be used.

Adjustment mechanisms 616 may be used to adjust the planar orientationand/or shape of the stiffener plate 202 with respect to the trussstructure 604 after manufacture of the probe card assembly 600 and/orbetween uses of the probe card assembly 600 to test dies (not shown). Inaddition, the adjustment mechanisms 616 may be used to adjust thestiffener plate 202 before bolting the probe card assembly 600 to thetest head plate 121 of a prober 102, while the probe card assembly 600is bolted to the test head plate 121, or after removing the probe cardassembly 600 from the test head plate 121.

The adjustment mechanisms 616 may also be used to adjust the stiffenerplate 202 during testing of dies (not shown) to counteract thermallyinduced movement of the stiffener plate 202 (or any other portion of theprobe card assembly 600). In response to detected movement of the probes224 during testing of dies (not shown), the adjustment mechanisms 616may be selectively activated to push or pull against selected regions ofthe stiffener plate 202 (as described above) to counteract the detectedmovement (that is, move the stiffener plate 202 such that the probes 224move back into their original positions).

Detection of movement of the probes 224 may be accomplished directly orindirectly in any suitable manner. For example, sensors may be used todetect such movement. In the example shown in FIGS. 7A and 7B, straingauges 622 can be disposed on the stiffener plate 202, which can includea cavity 638, to monitor the level of strain at particular locations onthe stiffener plate 202. Four such sensors 622 are illustrated in FIG.7A, although more or fewer sensors 622 may be used. Because the probehead assembly 222 is attached directly to the stiffener plate 202,monitoring strain on the stiffener plate 202 indirectly monitorsmovement of the probes 224. If sufficient strain is detected on thestiffener plate 202 to indicate that the probes have moved or are likelyto move, the adjustment mechanisms 616 may be selectively activated tocounteract the detected strain and/or predicted movement. Of course,sensors 622 other than strain gauges may be used. Examples of othersensors include laser-based sensors for monitoring movement of theprobes 224 or another part of the probe card assembly 600 and sensorsfor monitoring the electrical resistance of the contact connectionsbetween the probes 224 and the dies (not shown).

FIG. 8 illustrates a system for monitoring movement or deformation ofthe stiffener plate 202 and adjusting the stiffener plate 202 tocounteract the movement or deformation. Output 706 from sensors 622(e.g., strain gauges) can be processed by a processor 704 and theresults can be output 708 to a display 702. The processor 704 may be,for example, a microprocessor or controller running under software(including without limitation firmware or microcode) control, and thedisplay 702 may be a typical computer display. A human operator maywatch the display 702 and, after determining that the stiffener plate202 is undergoing movement or deformation, manipulate the adjustmentmechanisms 616 to counteract the movement or deformation. FIG. 8 alsoshows another alternative in which the processor 704 outputs controlsignals 710 to drive actuators 712 that turn nuts 634 to adjust thestiffener plate 202. For example, such actuators 712 may be precisionstepper motors (not shown).

FIGS. 9A and 9B illustrate yet another exemplary probe card assembly 900(which is shown in a prober 802). Probe card assembly 900 can begenerally similar to probe card assembly 600 and can include a probehead assembly 222, wiring board 204, stiffener plate 202, and trussstructure 604 that can be the same as like named and numbered elementsof probe card assembly 600. As shown in FIG. 9A, probe card assembly 900may also include a stud structure 820 that can be secured to the trussstructure 604. A moveable gripper 822 can be attached to the test head804, which may otherwise be similar to test head 104 in FIG. 1A (e.g., acable 810 or other communications media connects the test head 804 to atester (not shown)). The prober 802 may also be similar to prober 102 ofFIG. 1A. As shown in FIG. 9A, the probe card assembly 900 can be boltedvia bolts 842 to a prober head plate 834, which may be similar to proberhead plate 121 in FIG. 1A. Note that FIG. 9A includes cutout 850 toreveal probe head assembly 222 and stage 906 with dies 912. Stage 906can be like stage 106 of FIG. 1A, and dies 912 to be tested can be diesof an unsingulated semiconductor wafer (e.g., like wafer 112 of FIG.1A), singulated dies (e.g., held in a carrier (not shown)), dies forminga multi-chip module, or any other arrangement of dies to be tested.

As also shown in FIG. 9A, once the probe card assembly 900 is bolted(842) to the prober head plate 834, the gripper 822 can grip the studstructure 820. The gripper 822 can be attached to the test head 804 andthus adds the strength of the test head 804 in resisting thermallyinduced movement of the probe card assembly 900. As shown in FIG. 9A,the gripper 822 may be attached to a rigid bar, plate, or otherstructure 874 built into the test head 804.

As shown in FIG. 9B, the stud structure 820 can include a stud 830 andan attachment base 832 that can be attached to truss structure 604 bybolts, welding, or any other suitable means (not shown). The gripper 822can include an actuator 824 that moves vertically (relative to FIG. 9B)and may also be capable of horizontal and/or rotational movement. Arigid plate 825 can be attached to the actuator 824, and moveable arms826 can be attached to the rigid plate 825. Each moveable arm 826 caninclude a gripper pad 828.

Initially, actuator 824 can position the gripper 822 out of the way, asshown by dashed lines 890 in FIG. 9B. After the probe card assembly 900is bolted 842 to the prober head plate 834 (the probe card assembly 900is shown bolted 842 to the prober head plate 834 in FIG. 9A), theactuator 824 can align the gripper 822 with the stud 830, as shown bydashed lines 890 in FIG. 9B. The actuator 824 can then move the gripper822 such that the rigid plate 825 abuts against the stud 830, as shownby dashed lines 892 in FIG. 9B. Moveable arms 826 can then be moved suchthat gripper pads 828 grip the stud 830, as shown by the solid lines inFIG. 9B and in FIG. 9A. As mentioned above, the strength of the testhead 804 can thus be brought to bear against thermally induced “z”movement of the probe card assembly 900.

FIGS. 10A, 10B, and 10C illustrate still another exemplar probe cardassembly 1000, which as shown in FIGS. 10A, 10B, and 10C, can include aprobe head assembly 222, wiring substrate 204, and stiffener plate 202similar to like named and numbered elements of probe card assembly 200.As shown in FIGS. 10B and 10C, the probe card assembly 1000 also caninclude a heat sink 1002 disposed on the front-side the probe cardassembly 1000. The heat sink 1002, which can include an opening 1004 forprobe head assembly 222, can be made of a material with a high thermalconductivity and can be attached to the stiffener plate 202 withattachment elements 1006 that also have a high thermal conductivity. Inthe example shown in FIG. 10C, each attachment element 1006 can includea screw 1008 that threads into a threaded stud 1014 on the heat sink1002. The screw 1008 passes through a threaded hole (not shown) in thestiffener plate 202 and a hole 1012 in the wiring substrate 204. Thehole 1012 in the wiring substrate may include extra space to allow thewiring substrate to expand and contract as discussed above with respectto FIGS. 2A, 2B, and 2C. The threaded studs 1014 can abut against thestiffener plate 202, and the studs 1014 and screws 1008 can be made of athermally conductive material.

It should be apparent that the heat sink 1002 and the thermallyconductive attachment elements 1006 can provide a plurality of pathswith a high thermal conductivity from the front-side of the probe cardassembly 1002 to the stiffener plate 202 (the back-side of the probecard assembly 1002). While the probe card assembly 1000 is bolted into aprober (e.g., like probe card assembly 900 in FIG. 9A), the heat sink1002 thus faces the stage (e.g., 906 in FIG. 9A) that holds the dies(not shown) being tested. If the stage is heated or cooled, or if thedies (not shown) generate or sink significant heat during testing, theheat sink 1002 and attachment elements 1006 can thus provide a pluralityof paths with low thermal resistance to conduct heat from the front-sideof probe card assembly 1000 to the back-side of the probe card assembly1000 or from the back-side to the front-side. This can decrease the timerequired for the front-side and the back-side of the probe card assembly1000 to reach temperature equilibrium and thus reduce the thermalequilibrium time of the probe card assembly 1000. This can also helpmaintain a temperature equilibrium between the front-side and theback-side of the probe card assembly 1000 during testing. The mechanicalfasteners 216 that attach the probe head assembly 222 to the stiffenerplate 202 (see FIG. 2C) may also comprise a thermally conductivematerial and thus provide additional paths with low thermal resistancefor conducting heat from the probe head assembly 222 (at the front-sideof the probe card assembly 1000) to the stiffener plate 202 (at theback-side of the probe card assembly 1000).

Although not shown in FIGS. 10A, 10B, or 10C, a thermally insulatingmaterial (not shown) may be placed around the stiffener plate 202 toslow or prevent heat transferred through the thermally conductive pathsdiscussed above (e.g., the heat sink 1002 and thermally conductiveattachment elements 1006 and/or the probe head assembly 222 and themechanical fasteners 216) to the stiffener plate 202 from being lost tothe ambient air around the stiffener plate 202. If a truss structure 604is attached to the stiffener plate 202 (as in FIG. 6), the thermallyinsulating material (not shown) may also be placed around the trussstructure 604. Although also not shown in FIGS. 10A, 10B, or 10C,thermal diodes could be placed in the thermally conductive paths betweenthe heat sink 1002 and the stiffener plate 202 and configured to switchoff and thus stop the conduction of thermal energy while temperatureequilibrium between the front-side and back-side of the probe cardassembly 1000 (or another predetermined condition) is achieved.

The exemplary probe card assembly 1110 shown in FIGS. 11A, 11B, and 11Cshows an alternative to a heat sink 1002. In the exemplary probe cardassembly 1100, fans 1102 pull air from the front-side of the probe cardassembly 1100 to the back-side of the probe card assembly 1100. As shownin FIGS. 11A, 11B, and 11C, the fans 1102 pull air from the front-sideof the probe card assembly 1100 through passages 1104 and 1106 in thewiring substrate 204 and stiffener plate 202 to the back-side of theprobe card assembly 1100. (Arrows 1110 show the direction of air flow.)Again, this can decrease the time required for the front-side and theback-side of the probe card assembly 1100 to reach temperatureequilibrium and thus reduce the thermal equilibrium time of the probecard assembly 1100. This can also help maintain a temperatureequilibrium between the front-side and the back-side of the probe cardassembly 1100 during testing, which can eliminate or at least reducethermally induced movement of the probe card assembly 1100 duringtesting of dies (not shown). Of course, each of air-flow passages 1104and 1106 could be replaced with multiple smaller passages. Fans 1102 andpassages 1104, 1106 can thus conduct heat from the front-side of probecard assembly 1100 to the back-side of the probe card assembly 1100 orfrom the back-side to the front-side.

FIGS. 12A and 12B illustrate a probe card assembly 1200 that can begenerally similar to probe card assembly 1100 of FIGS. 11A, 11B, and 11Cexcept that fans 1104 can be replaced by fan 1204 located in a cover1202. That is, a cover 1202 can be attached to the stiffener plate 202,forming a cavity 1206 as shown in FIG. 12B. Fan 1204 draws air from thefront-side of probe card assembly 1200 through passages 1104 and 1106 inthe wiring substrate 204 and stiffener plate 202. As shown in FIG. 12B,the air also passes through the cavity 1206, and as it does so passesover the stiffener plate 202. (Airflow is shown by arrow 1210.) Again,this can decrease the time required for the front-side and the back-sideof the probe card assembly 1200 to reach temperature equilibrium andthus reduces the thermal equilibrium time of the probe card assembly1200. This can also help maintain a temperature equilibrium between thefront-side and the back-side of the probe card assembly 1200 duringtesting, which can eliminate or at least reduce thermally inducedmovement of the probe card assembly 1200 during testing of dies (notshown). Fan 1204 and passages 1104, 1106 can thus conduct heat from thefront-side of probe card assembly 1200 to the back-side of the probecard assembly 1200 or from the back-side to the front-side. Each ofair-flow passages 1104 and 1106 could be replaced with multiple smallerpassages.

FIGS. 13A, 13B, and 13C show another exemplary probe card assembly 1300.The probe card assembly 1300 can include a mounting/wiring structure1302 and a probe head assembly 1322 with probes (probes 1324 a-d areshown), which can be generally the same as probes 224. Themounting/wiring structure 1302 (which is shown in partial view in FIGS.13A, 13B, and 13C) can provide both electrical wiring to and from theprobe head assembly 1322 and a structure for mounting to a prober. Themounting/wiring structure 1302 is shown generically in FIGS. 13A, 13B,and 13C because it is intended that any structure suitable for bothproviding wiring to the probe head assembly 1322 and a structure formounting to a prober be represented. For example, the mounting/wiringstructure 1302 may be as simple as a standard wiring substrate, likewiring substrate 120 of FIG. 1A. Alternatively, mounting/wiringstructure 1302 may comprise one or more of a wiring board, stiffenerplate, truss structure, and stud structure similar to and configuredlike the wiring substrate 204 and stiffener plate 202 of FIGS. 2A, 2B,and 2C, the truss structure 604 of FIGS. 7A and 7B, and the studstructure 820 of FIGS. 9A and 9B. As yet another example,mounting/wiring structure 1302 may comprise a coaxial cable interface(not shown) or other such connector for interfacing with a tester (notshown). An example of a coaxial cable interface (not shown) is disclosedin U.S. Patent Application Publication No. 2002/0195265.

Probe head assembly 1322 may be generally similar to probe head assembly222 in FIGS. 2A, 2B, and 2C, and probes 1324 a-d may be similar toprobes 224 in FIGS. 2A, 2B, and 2C. As shown in FIGS. 13A, 13B, and 13C,the probe head assembly 1322 additionally can include one or moretemperature control device 1340.

It is sometimes desirable to test semiconductor dies over a range ofoperating temperatures. That is, while test signals can be passed to andfrom the dies via the probe card assembly, the temperature of the diesis changed from a lower temperature to a higher temperature (or visaversa). There is a potential problem, however. Because the dies and theprobe head assembly can be typically made of different materials withdifferent coefficients of thermal expansion, the dies and the probe headassembly expand or contract at different rates in response to thechanging temperature. For example, a probe head assembly may be made ofa ceramic material which can have a higher coefficient of thermalexpansion than silicon, which is a typical material of dies.

FIGS. 13A and 13B illustrate this problem. In FIG. 13A, the probes 1324a-d of probe card assembly 1300 can be brought into contact withterminals 1344 of one or more dies 1312 to be tested. (Dies 1312 can bedies of an unsingulated semiconductor wafer (e.g., like wafer 112 ofFIG. 1A), singulated dies (e.g., held in a carrier (not shown)), diesforming a multi-chip module, or any other arrangement of dies to betested.) (In FIGS. 13A, 13B, the mounting/wiring structure 1302, thesemiconductor dies 1312, and the stage 1306 are shown in partial view.As described above, the probe card assembly 1300 can be mounted in aprober (not shown), and the stage 1306 can be in the prober.) In thisexample, the temperature of the dies 1312 is raised, which causes thedies 1312 and the probe card assembly 1322 to expand in response to therising temperature. The dies 1312, however, expands at a greater ratethan the probe head assembly 1322, and eventually, as shown in FIG. 13B,the probes 1324 a-d no longer align with the terminals 1344 of the dies1312. In the example of FIG. 13B, probe 1324 d becomes so misalignedwith its corresponding terminal 1344 that contact between probe 1324 dand the terminal 1344 is lost. (The net expansion of the dies 1312 withrespect to the probe head assembly 1322 is represented in FIG. 13B byarrows 1330.)

The temperature control device 1340 of the probe head assembly 1322 canbe activated to correct the misalignment of the probes 1324 a-d and theterminals 1344. That is, the temperature control device 1340 can beactivated to heat the probe head assembly 1322 so that it expands asmuch as or approximately as much as the dies 1312. In FIG. 13C, theadditional expansion of the probe head assembly 1322 caused by thetemperature control device 1340 is represented by arrows 1332. As shownin FIG. 13C, this expansion causes the probes 1324 a-d to realign withterminals 1344.

Of course, the temperature control device 1340 could alternatively coolthe probe head assembly 1322 if cooling were needed to keep the probes1324 a-d aligned with the die terminals 1344 of the dies 1312 over agiven test temperature range. Indeed, by thus controlling thetemperature of the probe head assembly 1322 independently of thetemperature of the dies 1312, the dies 1312 can be tested over a greatertemperature range while keeping the probes 1324 a-d and the dieterminals 1344 aligned than would otherwise be possible. Temperaturecontrol device 1340 can thus be used to control positions (e.g., lateralpositions) of probes 1324 a-1324 d, such as during testing of dies 1312.

In one embodiment, the portion of the probe head assembly 1322 to whichthe probes 1324 a-d are mounted comprises a ceramic material and thedies 1312 comprises silicon. The probes 1324 a-d can be positioned onthe probe head assembly 1322 to align with the terminals 1344 on thedies 1312 while both the probe head assembly 1322 and the dies 1312 areat the highest temperature in the range of temperatures over which thedies (not shown) of the dies 1312 are to be tested. Thus, during testingof the dies of dies 1312, at the highest test temperature, the probes1324 a-d will naturally align with the die terminals 1344 without theneed to alter the temperature of the probe head assembly 1322, and atall lower temperatures, the probe head assembly 1322 can be heated bytemperature control device 1340 (which may thus be a heating device) tobring the probes 1324 a-d into alignment with the die terminals 1344.

In some embodiments, probe head assembly 1322 can comprise a multilayersubstrate comprising one or more layers of conductive material disposedbetween one or more layers of insulating material. FIG. 14 illustratesan example of such a multilayer substrate according to some embodimentsof the invention. As shown, probe head assembly 1322 can comprise aplurality of layers 1410, 1412 of an electrically insulating material(e.g., ceramic). (Although two layers 1410, 1412 are shown, more orfewer layers can be used.) Electrically conductive pads or traces 1402,1404, 1426 can be disposed on and between insulating layers 1410, 1412,and electrically conductive vias (not shown) can be provided through oneor both of layers 1410, 1412 to electrically connect pads or traces ondifferent layers. As shown in FIG. 14, probes 1324 a-d can be attachedto pads 1404, and pads 1402 can provide electrical connections tomounting/wiring structure 1302 (see FIG. 13C). Vias (not shown) throughlayer 1410, traces (e.g., 1426 between layers 1410, 1412, and vias (notshown) through layer 1412) can electrically connect ones of pads 1402with ones of pads 1404.

Temperature control device 1340 can comprise one or more of theconductive traces 1426 embedded between layers 1410, 1412. That is, oneor more of traces 1426 can comprise a material that generates heat inresponse to current passing through the material. Current can besupplied to the one or more of traces 1426 forming such heaters throughone or more of pads 1402 that are otherwise unused (e.g., notelectrically connected to a pad 1404 with a probe 1324 a-d). Current maybe provided to the temperature control devices 1426 through electricalconnections other than pads 1402. Regardless of how current is suppliedto the temperature control devices 1426, a current can be applied in anamount needed to heat the probe head assembly 1322 sufficiently to keepthe probes 1324 a-d aligned with the terminals 1344 of the dies 1312being tested as the temperature of the dies 1312 is changed during thetesting, as described above (see FIGS. 13A-13C).

Electrically conductive material that generates heat while a current ispassed through the material is but one example of temperature controldevice 1340. In other examples, temperature control device 1340 cancomprise tubes through which heated or cooled liquid or gas is passed.Moreover, temperature control device 1340 can be disposed on the outsideof probe head assembly 1322.

FIG. 15 illustrates a process 1500 for monitoring alignment of theprobes of a probe card assembly and the terminals of dies during testingof the dies as the temperature of the dies is varied and adjusting thetemperature of the probe head assembly as needed to compensate for anydetected misalignment. FIG. 16 illustrates a simplified block diagram ofa system 1600 for implementing the process of FIG. 15, and FIG. 17illustrates an exemplary test head 1704 and prober 1704 on which theprocess of FIG. 15 may be used.

As shown in FIG. 15, process 1500 can begin with installation of a probecard assembly in a prober (1502). Referring to the example shown in FIG.17, probe card assembly 1300 (which, as described above can include amounting/wiring structure 1302 and a probe head assembly 1322) can bebolted to the prober head plate 1732 of prober 1702. Referring again toFIG. 15, the probes of the probe card assembly can then be brought intocontact with the terminals of dies to be tested (1504). For example, asshown in FIG. 17, a dies 1312 can be placed on a stage 1706 in theprober 1702, and the stage 1706 can move terminals 1321 of the dies (notshown) of the dies 1312 into contact with the probes 1324 of the probecard assembly 1300. At 1506 of FIG. 15, the dies can be tested. In theexample shown in FIG. 17, a tester (not shown) generates test data thatcan be communicated via cable 1710 to test head 1704 and through probecard assembly 1300 to the dies (not shown) of dies 1312, and responsedata generated by the dies (not shown) can be communicated through theprobe card assembly 1300, test head 1704, and cable 1710 back to thetester (not shown). (Connections like 114 in FIG. 1A, although notshown, can be present, connecting the test head 1704 to the probe cardassembly 1300.) At 508 of FIG. 15, as the dies are being tested at 1506,the temperature of the dies can be varied. For example, the stage 1706in FIG. 17 may include a heater and/or cooler for heating and/or coolingthe dies 1312. While testing the dies at 1506 and varying thetemperature of the dies at 1508, the process of FIG. 15 determineswhether the probes and the die terminals are still properly aligned at1510. If yes, the process 1500 of FIG. 15 continues to test the dies at1506, vary the temperature of the dies at 1508, and monitor alignment ofthe probes and die terminals at 1510. If, however, it is determined at1510 that the probes and the die terminals are no longer in properalignment, the process 1500 changes the temperature of the probe headassembly at 1512 and then rechecks the alignment at 1510 until theprobes and terminals are again in alignment as shown in FIG. 15.(Although not shown, provisions can be provided for terminating theprocess 1500 of FIG. 15 after 1506 once testing of the dies iscompleted, after repeating 1512 and 1510 a number of times withoutsuccessfully bringing the probes and terminals into alignment, or forother reasons.)

FIG. 16 illustrates an exemplary system for implementing 1510 and 1512of FIG. 15. As shown in FIG. 16, system 1600 can include a processor1604 that operates in accordance with software (including withoutlimitation microcode or firmware) stored in memory 1604. The processor1604 can receive input 1610 from a monitor 1606, determine whether theinput 1610 from the monitor 1606 indicates that the probes and dieterminals are out of alignment (1510 of FIG. 15), and if so, can outputcontrols signals 1612 to temperature control devices 1608 in the probehead assembly (1512 of FIG. 15). The temperature control devices 1608may be any of the temperature control devices discussed above withrespect to FIGS. 13A-13C and 14A-14D.

The monitor 1606 may be any device or system for determining directly orindirectly that the probes are out of alignment with the die terminals.FIG. 17 illustrates one such exemplary monitor 1606. In FIG. 17,alignment marks 1724 can be placed on the probe head assembly 1322.Corresponding alignment marks 1726 can be placed on the dies 1312. Whilemarks 1724 on the probe head assembly 1322 are aligned with thecorresponding marks 1726 on the dies 1312, the probes 1324 are properlyaligned with the die terminals 1321. Cameras 1720 and 1722 in prober1702 may be used to determine whether alignment marks 1724 on the probehead assembly 1322 are aligned with the corresponding alignment marks1726 on the dies 1312. Monitor 1606 of FIG. 17 may thus comprise thecameras 1720 and 1722, and input 1610 to processor 1604 may compriseimage data produced by the cameras 1720 and 1722.

Of course, the cameras 1720 and 1722 are but one example of a monitor1606 that may be used with the system 1600 of FIG. 16. As anotherexample, alignment marks 1724 and 1726 may be replaced with probes onone of the probe head assembly 1322 or the dies 1312 and target pads onthe other of the probe head assembly 1322 or the dies 1312 in which thetarget pads output signals corresponding to the position of the probeson the target pads, such signals indicating relative movement of theprobe head assembly 1322 with respect to the dies 1312.

As an alternative to the feedback controlled process 1500 shown in FIG.15, the system of FIG. 17 could be operated without feedback control.That is, the system of FIG. 17 could be operated without monitoringalignment of the probes 1324 with the die terminals 1726 at 1510.Instead, the temperature of the probe head assembly 1322 could bechanged at 1512 in accordance with changes to the temperature of thedies of dies 1312 at 1508. Such a simplified version of the process 1500of FIG. 15 may be particularly useful where the relationship between thepositions of probes 1324 and the temperature of the dies 1312 is knownand predictable.

FIG. 18 shows an exemplary probe head assembly 1322, which is anotherexample of an implementation of probe head assembly 1322 shown in FIGS.13A, 13B, and 13C. As shown in FIG. 18, the probe head assembly 1322comprises a plurality of probe substrates 1808 (two are shown, althoughmore than two may be included). A plurality of probes 1812 (which can bethe same as probes 224) can be attached to each probe substrate 1808 andarranged to contact the terminals of dies (not shown) to be tested. Eachprobe substrate 1808 can be attached to an attachment structure 1802,which among other things, attaches to a mounting/wiring structure 1302as shown in FIG. 13A and discussed above. The probe substrates 1808 maybe attached to the attachment structure 1802 in any suitable manner,including without limitation using bolts, screws, clamps, adhesives,etc.

As shown in FIG. 18, each probe substrate 1808 can include a temperaturecontrol device 1810 to expand and contract the probe substrate 1808 asgenerally discussed above with respect to FIGS. 13A, 13B, and 13C. Asalso shown in FIG. 18, the attachment structure 1802 also can include atemperature control device 1804 to expand and contract the attachmentstructure 1802 in the same general manner as discussed above withrespect to FIGS. 13A, 13B, and 13C. Because the probe substrates 1808are attached to the attachment structure 1802, expanding or contractingthe attachment structure 1802 affects the positions of the probesubstrates 1808. The temperature control devices 1804 and 1810, whichmay be generally similar to temperature control device 1340 in FIG. 13A,thus provide two levels of control for positioning the probes 1812 withrespect to die terminals (not shown) on dies (not shown) being tested:the temperature control device 1804 in attachment structure 1802 affectsthe positions of probe substrates 1808, and the temperature controldevice 1810 in each probe substrate 1808 affects the positions of theprobes 1812 attached to the probe substrate 1808.

As an alternative to the temperature control device 1340 shown in FIGS.13A, 13B, and 13C (or the temperature control devices 1426 shown inFIGS. 14C and 14D), a mechanical force could be applied to the probehead assembly 1322 to stretch or compress the probe head assembly 1322so that it expands or contracts to match expansion or contraction of thedies 1312 under test (as generally shown in FIGS. 13A, 13B, and 13C).For example, threaded studs (not shown) could be attached to peripheraledges of the probe head assembly 1322, and threaded actuators (notshown) used to apply tensile or compression forces to the probe headassembly 1322 to stretch or compress, respectively, the probe headassembly 1322. As an example, such tensile forces could be applied tothe probe head assembly 1322 to stretch (expand) the probe head assembly1322 as shown in the transition from FIG. 13B to FIG. 13C (asrepresented by arrow 1332 in FIG. 13C). As yet another alternative, boththe temperature control device 1340 and a mechanical device for applyingmechanical forces to the probe head assembly 1322 could be used toexpand or contract the probe head assembly 1322. In like manner,mechanical devices (not shown) for applying mechanical forces to theattachment structure 1802 and the probe substrates 1808 of FIG. 18 couldbe used in place of or in conjunction with the temperature controldevices 1804 and 1810 of FIG. 18.

The various techniques described herein may be used together in variouscombinations. FIG. 19 illustrates an exemplary probe card assembly 1800that can include a wiring board 204 and stiffener plate 202 as describedabove respect to FIGS. 2A, 2B, and 2C. The probe card assembly 1800 alsocan include a truss structure 604 as described above with respect toFIGS. 6, 7A, and 7B. A stud structure 820 like the stud structuredescribed with respect to 9A and 9B can be attached to the trussstructure 604. Probe card assembly 1800 also can include a heat sink1002 as described above with respect to FIGS. 10A, 10B, and 10C. Probecard assembly 1800 can include a probe head assembly 1322 withtemperature control device 1340 as described above with respect to FIGS.13A, 13B, 13C, 14A, 14B, 14C, and 14D. The probe card assembly 1800 ofFIG. 19 thus combines features from the probe card assemblies 200, 600,900, 1000, and 1300.

Other combinations are possible. For example, the probe card assembly1800 could include fans like fans 1102 or 1204 and air passages like airpassages 1104 and 1106 in probe card assemblies 1100 and 1200 in placeof or in addition to the heat sink 1002. As another example, the trussstructure 604 could be removed from the probe card assembly 900, and thestud structure 820 could be attached to the stiffener plate 202. As yetanother example, a truss structure 604 could be attached to thestiffener plate 202 (as shown in FIGS. 7A and 7B) of the probeassemblies 1000, 1100, or 1200. Still other combinations are possible.

Although exemplary embodiments and applications of the invention havebeen described herein, there is no intention that the invention belimited to these exemplary embodiments and applications or to the mannerin which the exemplary embodiments and applications operate or aredescribed herein. Indeed, many variations and modifications to theexemplary embodiments are possible. For example, although each of theembodiments is described herein in the context of testing semiconductordies, the invention is not so limited but is applicable to anyapparatus, system, or scenario in which a device is tested or monitoredby probing the device.

As another example, some of the exemplary card assemblies illustratedand described herein are shown with one probe head assembly (e.g., 222shown in FIG. 2C, among other figures), any of those probe cardassemblies may be configured with more than one probe head assembly eachcomprising a set of probes, and the probe head assemblies can bedisposed to form a large array of probes comprising the sets of probeson each of the probe head assemblies. Non-limiting examples of probecard assemblies with a plurality of probe head assemblies are shown inU.S. patent application Ser. No. 11/165,833, entitled “Method AndApparatus For Adjusting A Multi-Substrate Probe Structure,” filed Jun.24, 2005. Such probe card assemblies may be configured such that eachprobe head assembly is individually moveable independent of the otherprobe head assemblies.

1-31. (canceled)
 32. An apparatus for reducing an amount of timerequired for a probe card assembly for testing semiconductor devices toreach a desired temperature, comprising: a probe head assembly having afirst side and a second side, terminals located on the first side at apitch different from terminals located on the second side, respectiveones of the terminals on the first side being electrically connected toterminals on the second side through the probe head assembly, and havinga plurality of probes mounted to respective terminals on the first side;and a temperature control device of the probe head assembly configuredto adjust a temperature of the probe head assembly in accordance withthe desired temperature to reduce the amount of time required to reachthermal equilibrium.
 33. The apparatus of claim 32, wherein the probehead assembly comprises a multilayer ceramic structure.
 34. Theapparatus of claim 33, wherein the temperature control device is aheater embedded in the probe head assembly.
 35. The apparatus of claim34, wherein the probe head assembly has a coefficient of thermalexpansion greater than that of the semiconductor devices.
 36. Theapparatus of claim 32, wherein the probe head assembly comprises aplurality of probe substrates, each probe substrate having a respectivetemperature control device.
 37. A probe card assembly for testingsemiconductor devices, comprising: an attachment structure; at least oneprobe head assembly attached to the attachment structure composed of asubstantially rigid material and having a first side and a second side,terminals located on the first side at a pitch greater than terminalslocated on the second side, respective ones of the terminals on thefirst side being electrically connected to terminals on the second sidethrough traces embedded in the probe head assembly extending from thefirst side to the second side, and having a temperature control deviceconfigured to adjust a temperature of the probe head assembly inaccordance with a desired temperature to reduce an amount of timerequired to reach the desired temperature; a plurality of resilientprobes attached to respective terminals on the second side of the probehead assembly and extending from a surface of the second side of theprobe head assembly in a direction away from the second side of theprobe head assembly; a stiffening structure disposed on a side of theattachment structure opposite the side that the at least one probe headassembly is attached, providing stiffness in a direction normal to thefirst surface of the probe head assembly; and a plurality of adjustmentmechanisms extending through the stiffening structure and coupled to afirst surface of the attached structure for adjusting an orientation ofthe first surface of the support structure relative to a surface of thestiffening structure such that the adjustment is fixedly maintained. 38.The probe card assembly of claim 37, further comprising: a multi-layercircuit board substrate disposed between the stiffening structure andthe attachment structure having a plurality of connectors on a firstside and wiring terminals on a second side, the plurality of connectorselectrically connected to the wiring terminal via conductive tracesembedded in the multi-layer circuit board, the first side having asurface area greater than a surface area of the first side of the probehead assembly, and wherein the second side of the multi-layer circuitboard is disposed closer to the first side of the probe head assemblythan the second side of the probe head assembly; a plurality ofconductive resilient elements disposed between the at least one probehead assembly and the multi-layer circuit board electrically connectingones of the terminals on the first side of the probe head assembly toones of the wiring terminals on the second side of the multi-layercircuit board.
 39. The probe card assembly of claim 37, wherein the atleast one probe head assembly comprises a multilayer ceramic structure.40. The probe card assembly of claim 39, wherein the temperature controldevice is a heater embedded in the attachment structure.
 41. The probecard assembly of claim 39, wherein the temperature control device is onan outer surface of the attachment structure.
 42. The probe cardassembly of claim 41, wherein the probe head assembly has a coefficientof thermal expansion greater than that of the semiconductor devices. 43.A method of reducing an amount of time required for a probe cardassembly for testing semiconductor devices to reach a desiredtemperature, comprising: providing a probe head assembly having aplurality of probes mounted thereon; and activating a temperaturecontrol device of the probe head assembly to adjust a temperature of theprobe head assembly in accordance with the desired temperature to reducethe amount of time required to reach the desired temperature.
 44. Themethod of claim 43, wherein the desired temperature is independent of anambient temperature.
 45. The method of claim 44, wherein the activatingcauses the probe head assembly to increase in temperature.
 46. Themethod of claim 44, wherein the activating causes the probe headassembly to decrease in temperature.
 47. The method of claim 43, whereinthe adjusting is controlled independently of a temperature of thesemiconductor devices.
 48. The method of claim 43, further comprisingproviding the probe head assembly as a multilayer ceramic structure. 49.The method of claim 48, further comprising providing the temperaturecontrol device as a heater embedded in the probe head assembly.
 50. Themethod of claim 43, further comprising providing the probe head assemblyhaving a coefficient of thermal expansion greater than that of thesemiconductor devices.
 51. The method of claim 50, wherein theactivating causes the probe head assembly to increase in temperature.52. The method of claim 43, further comprising providing the probe headassembly with a first side and a second side, wherein terminals on thefirst side are provided at a pitch different from terminals provided onthe second side, respective ones of the terminals on the first side areelectrically connected to terminals on the second side through the probehead assembly, and the probe are mounted to respective terminals on thefirst side.
 53. The method of claim 52, further comprising: providing awiring substrate disposed nearer to the second side than the first side;providing a control signal to control the temperature control devicethrough the wiring substrate to a point on the second side.
 54. Themethod of claim 43, further comprising selecting the desired temperaturein accordance with a temperature of the semiconductor devices.
 55. Themethod of claim 43, further comprising providing the probe head assemblyhaving a plurality of probe substrates.
 56. The method of claim 43,wherein the adjusting is controlled in response to a temperaturevariance near the probes.
 57. The method of claim 43, wherein theadjusting is controlled in accordance with a measurement of the probecard assembly.
 58. The method of claim 43, wherein the probe headassembly comprises a plurality of probe head assemblies having a portionof the plurality of probes mounted thereon the probe head assemblyattached to an attachment structure, wherein the temperature controldevice adjusts a temperature of the attachment structure.